1. Field of Industrial Utility
This invention relates to the retarding control apparatus in which use is made of a retarder mounted on an engine or in a power transmission system to absorb a reverse driving force from an automotive vehicle and apply a braking force to the vehicle.
2. Prior Art
FIG. 7 illustrates the retarder control circuit of a retarding control apparatus using an exhaust brake in accordance with the prior art. The control circuit is described in the Toyota Toyace manual (1985-8) and Toyota Dyna Manual (1980-9).
3. Analysis of the Prior Art
The circuit shown in FIG. 7 includes an exhaust brake computer A, a fuel control relay B, a fuel control motor C, a starter motor 1, an ignition switch 2, a neutral switch 3, an auxiliary starter switch 4, a main switch 5, an accelerator switch 6, a clutch switch 7, an exhaust brake indicator lamp 8, an oil lamp 9, an oil pressure switch 10, an exhaust brake solenoid 11 and a speed sensor 12. The exhaust brake computer A includes a low-speed cancelling circuit 13. In the fuel control motor C, X represents a fuel increasing position, Y a drive position and Z a stop position.
Retarder control is performed by controlling the opening and closing of an exhaust brake valve, not shown. The retarder operating conditions are as follows. Specifically, when all of the following conditions are satisfied, the exhaust brake valve is closed and a braking force acts upon the vehicle owing to the pumping action of the engine:
(1) the driver's foot is removed from the accelerator pedal;
(2) the driver's foot is removed from the clutch pedal;
(3) the vehicle velocity is 15 km/h or more;
(4) the neutral switch 3 is turned off; and
(5) the main switch 5 is turned on.
The retarding action cancellation condition is either of the following:
(6) when the vehicle velocity falls to 10 km/h or below;
(7) when any one of the operating conditions (1), (2), (4) and (5) is not satisfied.